Moulds made from aluminium its alloys are in common use in the rubber moulding industry. These moulds have several advantages. They are easy to cast and machine and moulds with intricate patterns in their cavities can be cast or machined with little difficulties. In addition moulds made from aluminium or its alloys are relatively lighter as they have lower material densities. This facilitates their handling, reducing mould changing times and easing other related activities. Aluminium and its alloy are not expensive raw materials and with the above mentioned benefits moulds made from them are relatively cheaper overall as compared with moulds made from other materials. However aluminium or its alloy as mould material is not without disadvantages. Aluminium and its alloy are in general softer as compared to steel or cast iron. Being softer, deformations of the mould walls and to a lesser extent the mould body and the mould cavity can happen with repeated usage, all of which lead to some extend changes in dimensional properties of the moulded products. Due to their relative softness there are limits to the moulding pressures with moulds made from aluminium or its alloy.
It is under the above circumstances that the present invention introduces a method of strengthening a mould of aluminium or its alloy as the base material in order to extend its service life.